At petroleum storehouses, installations and/or industries, tanks and reservoirs are generally used to store petroleum (crude oil), so that, later on, it is processed or transported to other places.
However, such tanks, as they are used over time, build up solid and/or liquid compounds and residues inside them, mainly on the inner surfaces of their walls, their bottom and lid or ceiling. Such residues form mud and sludge which, if not removed periodically, reduce the storage capacity of the tank, a fact obviously unwanted. Moreover, the excess of residues may worsen the quality of the petroleum to be delivered at oil refineries.
Apparatuses which can reduce the volume of mud and sludge and the amount of residues present on the tank bottom are already known.
For instance, patent document EP 1106269 proposes a cleaning apparatus which, in theory, can clean the bottom of a tank for crude oil storage by discharging a fluid stream. Such apparatus comprises a sphere, assembled on a lower portion of the tank wall, having an internal passageway which allows the flow of pressurized fluids coming from a pump to reach the bottom of the tank. This pump reuses the very crude oil from the tank as a cleaning fluid in order to remove unwanted solid or liquid residues. Besides, the apparatus also has an actuator able to move the sphere rotationally. However, as the sphere is fixed on the apparatus by two locking pins diametrically positioned opposing to each other; it can revolve only around one single geometrical central axis, once its movement towards other angle directions is impossible due to the restriction imposed by these two pins.
Therefore, the constructive arrangement and structure of the apparatus described on patent EP 1106269 restrict the rotational movement of the sphere, allowing it to rotate just around a single geometrical central axis, which impairs its capacity to remove mud or sludge. Thus, cleaning the bottom of the tank becomes difficult or even impossible in some specific areas, once the apparatus cannot reach its whole region. Moreover, it is impossible to remove residues from other portions inside the tank, such as the internal surfaces of its wall and lid or ceiling, once a multidirectional movement cannot be imposed to make the sphere revolve around several geometrical axes.